A standard tennis racket such as described in French Pat. No. 2,455,906 has an elongated handle defining a longitudinal axis and having an inner end provided with a grip and an outer end that forks and that forms the throat of the head of the racket. The head in turn is invariably oval, annular, and bisected by the main longitudinal axis. It carries an array of transversely equispaced longitudinal or main strings and an array of longitudinally spaced cross strings woven and forming a plane with the main strings. The outer periphery of the head is formed with an outwardly open groove in which the strings run, as in reality only a single filament forms all the cross strings and at most one other itself forms all the main strings. This groove protects the strings by recessing them so that they are not damaged if, for instance, the edge of the racket's head is struck on the ground. Typically grommets, eyelets, or the like are used to line the holes in the frame through which the strings pass to reinforce the material of the racket, as there is considerable tension in the strings at all times, and this tension peaks very high when a ball is struck.
In order to give the most even response in the central sweet spot of the racket, where the ball should be struck for most effective response of the racket, it is known to provide a reverse or crowned throat on the frame having a curvature identical to the opposite end or crown of the head and concave toward the handle, like the crown. The longitudinal strings that lie in the sweet spot therefore are all of the same length, measured in the plane of the strings within the inner periphery of the racket, so that they will have substantially the same response.
Although it has been suggested to make the cross strings also of equal length in the sweet spot at least, no practical way of achieving this end has been found. The logical procedure is to make both of the sides, that is the parts of the frame at the head between the crown which is most distant from the handle and the throat which is at the outer end of the handle, straight. This has two main disadvantages: The resultant racket looks so nonstandard as to be unmarketable, and the use of straight sides substantially weakens the racket. Thus a square-sided racket, if it looked good enough to be acceptable, would have to be made very robustly to have the same strength as the inherently stronger oval shape of a standard racket. Such construction would substantially increase the weight of the racket and make it for this reason unusable. If on the other hand some inward bending of the sides were tolerated, the result would actually be a nonuniform response since the bending would be less toward the crown and throat, so that the desired effect would not be achieved.